Propeller



March 21, 1933. F. A. A. PEARSON PROPELLER Filed Jan. 3, 1931 INVENTOR FRfD 14.14. PEARSON BY ATTORNEY Patented Mar. 21, 1933 UNITED STATES PATENT OFFICE FREDA. .A..PEABSON, OF VALLEY STREAM, NEW YORK, ASSIGNOR TO CURTISS AERO- PLANE & MOTOR COMPANY, INC.,

A CORPORATION OF NEW YORK PROPELLER- Application filed January 3, 1931. Serial m. 506,392.

My invention relates to propellers for aircraft and is more particularly concerned with-propellers having detachable blades adjustable as to pitch. The propeller described herein is in some respects an improvement on the propeller described in a copending application of Werner-J. Blanchard, Serial Number 334,674.

One of the objects of this invention is to provide a new and improved structure by which the propeller blade is firmly secured within the hub.

A further object of the invention is toprovide a propeller structure having a hub with substantially straight sides and having me ans utilizing the centrifugal force generated by the rotation of the propeller to anchor the propeller blade within the hub more firmly.

Further objects will be apparent from a reading of the subjoined specification and claims and from a consideration of the accomp anying drawing.

In order to explain the invention more clearly, one embodiment thereof is shown in said drawing, in which:

The figure is a view partly in elevation and partly in vertical section of the hub portion and a portion of the blades of a propeller constructed according to my invention.

Therein,- I have shown a cylindrical hollow hub 8 having substantially straight exterior sides. The hub is formed with sockets of which the inner ends are formed with bevels as at 11. The hub is interiorly threaded at each end as at 12. Outward from the threads 12 the diameter of inner opening or socket of the hub is increased by a reduction in thickness of the hub so as to form a reduced extension of the cylindrical hub 13. The hub is provided with a transverse opening 14 into which an engine shaft is adapted to be inserted in order to drive the propeller.

Inserted within the socket of the hub 8 is the. butt or inner end of the propeller blade 15 which is constructed in a new and improved shape according to my invention. The intermediate portion of they propeller blade is formed with substantially straight sides so that the blade has a substantially uniform diameter as at 16. Inward of said portion 16 the butt end of the propeller slopes as at 17 to a portion of-uniform reduced diameter 18. Inward of the reduced portion 18 there is formed an enlarged inner end 19 of uniform diameter, there being formed an inclined shoulder 21 intermediate the portions 18 and 19 and inward of the portion 19 there being formed a reversely inclined shoulder 22. The

inclined face 22 cooperates with the bevel part of the socket 11 to further aid in this process.

Means are provided for hearing on the inclined face 21 for securi g the blade within the socket against the action ofcentrifugal force and for further aiding in centering the blade. A split nut or sleeve 23 is formed in two halves so that when assembled the two halves form a cylindrical sleeve. The halves are maintained in position when assembled by means of dowel pins such as the pins 24, 26. The lower end of the split sleeve 23 is formed with an inclined shoulder 28 which cooperates with the shoulder 21 to secure the blade within the socket and to center the blade as. mentioned above. The split sleeve 23 is moreover formed with an exterior thread 29 which is screwed into the interior thread 12 of the hub 8. The split sleeve is furthermore formed with an enlarged portion 31 which fits within the reduced portion 13 of the hub. It is to be noted that the action of centrifugal force in urging the blade 15 outward causes the bevel faces 21 and 28 to cooperate to secure the blade more tightly and to assist in maintaining the threads 29 and 12 from turning relative to each other.

I moreover provide-means by which the blade is firmly secured at-a point spaced outward from the inner end thereof. The outer end of the split sleeve 23 extends outward a substantial distance and is formed with an inclined face as at 32. Cooperating with this inclined face is a conically shaped ring 33 which surro-unds the portion 16,0f the blade portion 16 of the blade 15 to hold the blade 15 firmly. It is to be especially noted that the nut 35 has an exterior diameter substantially the same as that of the nut 23 so that the exterior surface of the assembly presents a substantially smooth surface.

In the assembly of my improved propeller the nut 35 is first slipped onto the butt end of the blade. Thereafter, the'conical ring 33 is slipped on to the butt end of the blade. Next, the split ring 23 is assembled around the blade so that it overlaps the ring 33 and so that its inclined surface 28 loosely contacts with the inclined surface 21. The assembly is next screwed into the hub 8. In this assembly process the inner end of the blade is screwed in until the inclined surface 22 contacts with the inclined surface 11 and the shoulder on the enlarged portion 31 of the split sleeve 23 contacts with the shoulder formed on the hub 8 by the reduced portion 13. The contact of these parts positions the blade exactly as desired. Next, the nut 35 is tightened on to the conical ring 33 and a. firm support is secured around the portion 16 of the blade 15. In the operation of the propeller centrifugal forces acting on the blade, force it outward so that the bevel faces 22 move away from the inclined surface 11 and said shoulders move out of contact with each other as is clearly shown in the drawing. The bevel face 21 wedges against the bevel face 28 to firmly lock the blade in position and to assist in preventing the threads 12 and 29 against turning relative to each other.

It is clear that in the construction shown a duralumin blade may be used while the hub. split sleeve and conical ring may all be of steel. Thus one of the inclined contacting surfaces at 21 and 28 is of steel while the other is of duralumin andthus the best possible bearing contact is obtained. Moreover, the screw threads are formed in the steel elements and thus the difiiculty of forming threads in duralumin is eliminated. I

It is to be understood that the above described embodiment of the invention is for the purpose of illustration only, and various changes may be made therein without departing from the spirit or scope of the invention.

I claim as my invention:

1. In an aeronautical propeller, a hub having a socket, a blade having an inner end adapted to be inserted within said socket, a split sleeve secured to said hub and adapted to bear upon said blade for securing it within said socket and having an outward extension,

a cone ring surrounding said blade and inserted within said extension, and means for drawing said cone ring longitudinally of said blade for wedging said blade within said extension.

2. In an aeronautical propeller, a hub having a socket, a blade having a butt end adapted to be inserted within said socket, a split nut adapted to be screwed into said hub and to bear on the inner end of said blade for securing said blade within saidsocket, and dowel pins for assisting in holding said nut in assembled relation.

3. In an aeronautical propeller, a blade having a butt, a hub having a socket into which the butt of said blade is adapted to be inserted, said hub being formed with internal threads and being formed with substantially straight external sides and having an extension with an opening of enlarged diameter, and a split ring adapted to be threaded into said hub and having a shoulder adapted to fit within said enlarged opening.

4. In an aeronautical propeller, a hub having a socket, a blade having a butt end adapted to fit within said socket, a split ring adapted to be secured to said socket and to bear on said butt end. of the blade for securing the blade within the socket, a cone ring adapted to surround said blade and be enclosed within said split ring for wedging said blade within the split ring, and a nut adapted to be threaded upon said Come.

5. In an aeronautical propeller, a hub, a

blade having an inner end adapted to be inserted within said hub, and a split nut adapted to be screwed into said hub and to bear on the inner end of said blade for securing said blade within said hub.

6. In an aeronautical propeller, a hub, a blade having an inner end adapted to (be inserted within said hub, said inner end of said blade having an inclined shoulder, and a split nut adapted to be screwed into said hub, said nut having an inclined shoulder adapted to bear against the inclined shoulder on said blade for securing said blade within said hub, said engaging shoulders being disposed adjacent to and inward of the screw threaded connection between said nut and said hub.

7. In an aeronautical propeller, a hub, a blade adapted to have itsinner end inserted into said hub, a sleeve surrounding said inner end of said blade and secured in said hub, said sleeve having the inner surface of its outer end outwardly tapered, a ring surrounding said inner end of said blade and having its outer surface inwardly tapered and adapted to bear against the inner tapered surface of said sleeve, and means for draw-' ing a socket with threads formed on the interior surface thereof, a blade having an en-. larged inner end adapted to be inserted in said socket, an externally threaded split nut adapted to be screwed within said socket threads and being adapted to engage said enlarged end for holding said blade within said socket, and means remote from the inner end of said blade for holding said blade in v alinement with said socket.

10. In an aeronautical propeller, a hub having a socket, a blade having an enlarged inner end adapted to be inserted in said socket, means bearing against said enlarged end and interlocking with said socket for holding said blade therewithin, said means having associated therewith at its outer end a tapered ring engageable with said blade for holding said blade in alinement.

11. In an aeronautical propeller, a blade having an enlarged inner end formed with an inclined surface extending outward from said end, a hub having a blade socket for the reception of said blade end, said socket having threads formed therein, and means for retaining said blade within said socket comprising a split nut surrounding said blade, said nut being exteriorly threaded to engage said socket threads, and having at its inner end an inclined surface coacting with said inclined blade surface.

12. In an aeronautical propeller, a hub having formed therein a blade socket, a blade adapted to be inserted in said socket, means bearing on said blade adjacent the inner end thereof for holding said blade within and in alinement with said socket, said means coacting with said blade and said socket, and

a tapered connection associated with an outward extension of said means for holding said blade in alinement at a point remote from the inner end thereof.

In testimony whereof I hereunto aflix my signature.

FRED A. A. PEARSON. 

